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Astron. Astrophys. 361, L60-L62 (2000)

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Letter to the Editor

Detection of the H I n=22-21 Rydberg line in emission at the solar submillimetre limb

T.A. Clark 1, D.A. Naylor 2 and G.R. Davis 3

1 University of Calgary, Calgary, Department of Physics and Astronomy, Alberta T2N 1N4, Canada (taclark@acs.ucalgary.ca)
2 University of Lethbridge, Department of Physics, Lethbridge, Alberta T1K 3M4, Canada (naylor@uleth.ca)
3 University of Saskatchewan, Institute of Space and Atmospheric Studies, 116 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada (G.R.Davis@usask.ca)

Received 10 August 2000 / Accepted 4 September 2000


This letter reports the discovery of excess emission at the position of the HI n=22-21 Rydberg transition in submillimetre solar spectra taken at the extreme solar limb. This emission feature at 22.096[FORMULA]0.003 cm-1 shows significant limb brightening, reaching intensities of 11% above the adjacent spectral continuum with line shapes fitted best by Gaussian functions with widths of 0.018[FORMULA]0.004 cm-1. This measurement represents the highest-n Rydberg line of HI detected to date in the solar spectrum.

Key words: line: identification – Sun: atmosphere – Sun: general – Sun: infrared

Send offprint requests to: T.A. Clark

© European Southern Observatory (ESO) 2000

Online publication: October 10, 2000